Parametrics (1 Viewer)

[velox]

Parametric Equations

Find the Cartesian equation of the curves who parametric equations are:

10. x = cos 2t, y = cos t
0<=?<=0




12. x = 2cos?, y = ?3 sin ? 0<=?<=2?



13. x = cos 2t, y = sin t 0<=?<=?



14. x = 2t y = 1 - t
1 + t 1 + t 0<=?<=?

I tried 13, but got a marginally wrong answernot sure what went wrong. With the others I think u have to square them but to be honest Im not confident on whether my squaring is right.thanks for your help my working for question12 is attached.

 

[George W. Bush]

cos2x = cos^2x - sin^2x = 1 - 2sin^2x = 2cos^2x - 1

apply appropriately

 

[CM_Tutor]

10. x = 2y² - 1

12. Assuming the question means x = 2cos t, y = 3t * sin t, I get y = [3 * sqrt(4 - x²) / 2] * cos^-1(x / 2)

13. x = 1 - 2y²

14. y = 1 - x² / 4

 

[velox]

oh crap the symbols didnt show up, thanks guyz